1. Field of the Invention
This invention relates to fluid flow control valves and in particular to spool valve assemblies for use therein.
2. Description of the Background Art
In one form of fluid flow control valve, a spool is selectively positionable in a valve chamber so as to provide selective flow between a pressure port opening to the valve chamber and either of two different cylinder ports.
In such valves, it is desirable to connect the cylinder port acting as a return port to a tank port by conducting fluid flow therefrom around the end of the spool valve assembly to the tank port. Thus, depending on the direction of valve movement, the return fluid is conducted around either end of the selectively positioned spool valve assembly through suitable passages in the control valve block to the tank port.
As the end of the spool is moved to uncover the opening to the cylinder port, an abrupt delivery of the fluid occurs in the present valves. At the same time, the flow of the fluid tends to be generally transversely to the entrance to the tank port passage, causing turbulences within the valve. The resultant instability has long been a vexatious problem in connection with such valves.